XBox 360 Live/NCAA 2009 Questions

I'm out of the loop I guess here. I used to play a lot of Madden and NCAA while in College. I played mostly on PS2.

I just purchased an XBox 360 and I gotta tell ya, I don't know if it's because I'm used to the way PlayStation's worked but I'm having some real issues getting towards things and I don't have a clue where to start.j

First, how the hell do I accept an invitation for a game for NCAA 2009 on XBox Live. I keep getting challenges and I don't know where the "F" to go to accept.

I dunno so far this XBox Live isn't nearly as user friendly as PS2 (maybe PS3 I don't know) online gameplan. Not even close.

Second, anybody help out with this "Gamertag" BS? I dunno what the hell it does, what it means, what the heck the use for it is. All I know is, why can't I access all the crap unless I take out a game go to the XBox Menu? Anyway I can access that while playing a game?

I've got so many more questions and complaints, but I was told by so many that if you've already got a Blu-Ray DVD player (which I do) and you're just in it for the gaming experience XBox 360 is the way to go. So far I'm quite unimpressed.